Embodiments of the inventive subject matter generally relate to the field of communication networks, and, more particularly, to reducing common mode currents in powerline communication devices.
Powerline communication (PLC) is a wired communication technology that utilizes electrical power wiring for transmitting and receiving communication signals. PLC technology typically utilizes a powerline communication device to facilitate communication between electronic/electric devices (e.g., Computer, Washing Machine, Door Lock, Electric Motor, etc.). In a balanced PLC network, electrical currents of equal magnitude (differential mode currents) travel in opposite directions over the line and neutral wires. However, PLC devices often have an imbalance in the currents which travel through the line and neutral wires. The imbalance in currents may be due to variations in the impedance parameters, S-parameters, wire thicknesses, etc. This imbalance manifests itself as common mode currents which travel through the line and neutral wires in the same direction, and then return through a ground path (a path different from a protective earth wire). The imbalance in current between the line and neutral wires is mitigated somewhat by a coupling transformer. However, due to parasitic capacitances and non-ideal behavior, some of the common mode currents also couple through the transformer. Electromagnetic fields which are radiated by differential mode currents tend to be 180 degrees out-of-phase with respect to each other, and hence they cancel out. However, electromagnetic fields generated by common mode currents are in-phase and do not cancel out. The electromagnetic fields generated by common mode currents may result in electromagnetic emissions outside permissible range.